diff --git a/spec/ameba/severity_spec.cr b/spec/ameba/severity_spec.cr
index 633372b0..9fd17a21 100644
--- a/spec/ameba/severity_spec.cr
+++ b/spec/ameba/severity_spec.cr
@@ -34,7 +34,7 @@ module Ameba
       end
 
       it "raises when name is incorrect" do
-        expect_raises(Exception, "Incorrect severity name BadName. Try one of [Error, Warning, Convention]") do
+        expect_raises(Exception, "Incorrect severity name BadName. Try one of: Error, Warning, Convention") do
           Severity.parse("BadName")
         end
       end
diff --git a/src/ameba/rule/lint/missing_block_argument.cr b/src/ameba/rule/lint/missing_block_argument.cr
index b5420f4d..379bfa85 100644
--- a/src/ameba/rule/lint/missing_block_argument.cr
+++ b/src/ameba/rule/lint/missing_block_argument.cr
@@ -3,19 +3,15 @@ module Ameba::Rule::Lint
   #
   # For example, this is considered invalid:
   #
-  # ```
-  # def foo
-  #   yield 42
-  # end
-  # ```
+  #     def foo
+  #       yield 42
+  #     end
   #
   # And has to be written as the following:
   #
-  # ```
-  # def foo(&)
-  #   yield 42
-  # end
-  # ```
+  #     def foo(&)
+  #       yield 42
+  #     end
   #
   # YAML configuration example:
   #
diff --git a/src/ameba/severity.cr b/src/ameba/severity.cr
index ed350a96..19e5a809 100644
--- a/src/ameba/severity.cr
+++ b/src/ameba/severity.cr
@@ -41,7 +41,7 @@ module Ameba
     def self.parse(name : String)
       super name
     rescue ArgumentError
-      raise "Incorrect severity name #{name}. Try one of #{values}"
+      raise "Incorrect severity name #{name}. Try one of: #{values.map(&.to_s).join(", ")}"
     end
   end